Boat hull construction



, March 2, 1943. A. J. HIGGINS BOAT HULL CONSTRUCTION Filed oct. 10, 1940 2 sheets-sheet 1 Mal'h 2, 1943- A. J. HIGGINS 2,312,548

AT HULL CONSTRUCTION Fatented Mar. 2, i943 BOAT HULL CONSTRUCTKON Andrew J. Higgins, New Orleans, La., assigner to Higgins Industries, Inc., New Orleans, La., a corporation of Louisiana Application October 10, 1940, Serial No. 360,648

Claims.

This invention relates to the construction of wooden hulls of vessels, with a special reference to the positioning and securing of the longitudinal strlngers relative to the transverse members or frames, in the interest of imparting maximum strength and rigidity to the hull.

The general object of the invention can best be comprehended by contemplating the hull as a girder built to resist an inilnite variety of stresses assailing the hull from diverse directions, but to avoid unnecessary complication, it will suiiice to consider only those stresses which tend to deiiect the hull in a vertical plane. Such stresses ordinarily arise when the ends of the hull are buoyed by adjacent wave crests or while a crest passes beneath the hull. Such stresses are at a maximum when the Vessel is lifted in slings toward the ends, leaving the middle portion unsupported, such practice, of course, being limited to vessels under one hundred feet in length.

In the construction of wooden vessels, such stresses are resisted by longitudinal stringers which are placed with their greater cross-sectional dimensions in an upright direction and secured to each of the transverse frames, the stringers being arranged on opposite sides of the keel and at various heights above the keel,

These stringer's are generally bent toward the median vertical plane of the hull, particularly where they approach the bow and stern sections.

They may at the same time be bent upward from a horizontal plane, as a feature of design, and they certainly bend or deflect upwardly at the ends when the hull is supported between the wave crests or in slings.

By reason of the particular arrangement of these stringers it will be apparent that selected pairs one on either side of the keel may be effectively used as clamps to support transverse deck beams.

Other objects of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

In the drawings which accompany and form a part of the following specification, and throughout the several figures of which the same characters of reference have been employed to designate identical parts:

Figure 1 is a transverse section through a hull illustrating securing means between the stringers and the inclined frame members embodying the principles of the invention;

Figure 3 is a horizontal section taken along the line 3-3 of Figure l;

Figure 4 is a plan v'lew at a point of intersection between a Stringer and frame member;

Figure 5 is a perspective view showing the securing means between the Stringer and frame member at one of the points of intersection;

Figure 6 is a perspective view of the bow portion of the hull.v

Figure 7 is a side elevation of a hull, largely diagrammatical, showing the longitudinal stringers bent upwardly at the ends in a vertical plane.

Figure 8 is a plan view of the hull showing the stringers bent inwardly at the ends in a horizontal plane.

Figure 9 is a diagrammatic View showing comparative cross-sections of a Stringer, illustrating the diminution in eiective depth which a Stringer undergoes when bent simultaneously in two planes.

Referring now in detail to the several figures, these represent a wooden boat hull comprising the keel l to which are secured in known manner the several transverse frame sections 2 and 4, in vertical planes and at longitudinal spaced stations. As shown, the frame sections are secured to the keel by the metallic plates 3. The frames diverge laterally from the keel with various degrees of Obliquity. The frames 2, which are adjacent the mid-ship part of the keel, or the stern, have the least upward inclination while the frames near the bow portion of the hull are more steeply inclined. The longitudinal vstringers `5, which give longitudinal rigidity to the h ull, rest upon the several frames. A comparison of Figures 1 and 6 shows that the stringers 5 arc,` atlhigher levels with respect to the keel as they approach the bow than at the mid-ship section, or stern, implying that the stringers, incline upwardly at their ends. Figure 7indicates diagrammatically this upward inclination of the ends of the stringers.

Figure 8 lshows diagrammatlcally that the stringers converge towards the keel at their forward and rear ends.

lWhether the stringere bend upward in a ver tical plane or ,are horizontal is a mattertof hull design, but in' any event inasmuch as no wooden hull is absolutely rigid, when the Afront and rear of the hull are supported upon wave crests, or when the hull is lifted from the water in slings supporting its end portions, the stringers will be deected vertically upward at the ends.

It is, of course, wel1known to structural engineers that when a beam is bent upward at its front and rear ends and at the Same time is bowed in a horizontal plane, the beam undergoes a distortion which draws its depth dimension out of a vertical plane and causes it to nare in a manner diagrammatically indicated in Figure 9. This flare reduces the effective depth of the beam and to that extent weakens the resistance of the beam to further deflection in a vertical plane. In general, this departure of the depth dimension of the beam from the vertical is at a maximum towards the middle of the beam.

As a rule, in securing the stringers to the frames at the several frame sections, the frames g are notched or cut away to provide a seat not only deep enough merely to provide a horizontal seat for the stringer, but with additional depth 'to provide some substantial side support for the stringer againstl which it may be bolted. The depth of such notches necessarily materially weakens the frames. Furthermore, the bolts employed to secure the stringers to the frames necessarily fix the stringers to the frame at one point and permit its diversion from the vertical under the torsional stress incident to its bending upwardly adjacent to the ends.

The present invention in its specific embodiment comprises a pair of angle irons 6 and 1, which are preferably f suilicient length to extend depth-Wise over most of the frame and to extend above the frame sufllciently to embrace most of the depth ofthe stringer. The angle irons 6 and 1 are preferably used in pairs on the same side of the frame and securely bolted thereto, preferably at spaced points 8 and 9 as shown in Figure 6. The angle irons 6 and 1 are spaced apart a distance equal to the Width of the stringers with their correspondingly confronting flanges in a true vertical direction when the hull is on an even keel, and in contact with the opposite sides of the Stringer and securely bolted thereto, preferably at the spaced points I and i I shown in Figure 6.

The longitudinal series of pairs of spacedvertically positioned angle irons forms a channel in" which the stringer seats being held with its depth dimension in a. true vertical plane at each of the frame stations.

The technique of construction may involve setting the longitudinal series of pairs of angle irons so as to define the proper curvature of the stringer and then bending the stringer and forcing it into the seating space between the angle irons of the several pairs.

Another mode of procedure would be to first put the Stringer in place and then temporarily.

forcibly holdit with its depth dimension vertically in the several stations, while the angle irons are bolted in place.

By either mode of construction it is obvious that the stringer when properly secured between the angle iron flanges, is incapable of diversion from the vertical at any of the stations where it is so secured regardless of the degree to which its upper ends may be inclined. Thus the longitudinal stability of the hull is maintained in spite of unusual bending stress. It will be understood both from Figures 1 and 6 and particularly the latter, that it is only necessary to notch the frames to the slight depth necessary to provide horizontal seat I2 for the bottom of the stringer. 'Ihe slight side support afforded by the shoulder I3 of the notch is altogether negligible and not relied upon to resist the lateral diversion of the depth dimension of the stringer.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of the invention it will be understood to those skilled in the art that the speciiic details of construction or the particular arrangement of parts as described and illustrated, is by way of example'and not to be construed as limiting the Scope of the invention which is dened in the appended claims.

What I claim as my invention is:

1. Boat hull construction including a keel with i a series of longitudinally spaced transverse frame members, said'frame members arranged in pairs angularly disposed with respect to each other and the angularity of each pair varying from the angularity of other pairs, a longitudinal stringer resting upon said frame members, and rigid means xedly secured to a plurality of said frame members, each including a rectilinear angle iron having a portion extending above the frame member to which it is secured in a vertical direction when .the hull is on an even keel, having 'a vertical seating face engaging a side of said stringer and rigidly secured thereto for maintaining the depth dimension of said stringer vertical throughout.

2. Boat hull construction including a keel with a series of longitudinally spaced transverse frame members, said frame members arranged 4in pairs angularly disposed with respect to each other and the angularity of each pair varying from the? angularity of other pairs, a longitudinal Stringer resting upon said frame members, and rigid means rigidly secured to a plurality of said frame members each comprising portions laterally spaced, extending above .the frame members to which said means are secured, having confronting vertical seating faces engaging opposite sides of said stringer and rigidly secured thereto for maintaining the depth dimension of said stringer vertical throughout.

3. Boat hull construction including a keel with a series of longitudinally spaced transverse frame members, said frame members arranged in pairs angularly disposed with respect to each other and the angularity of each pair varying from the angularity of other pairs, a longitudinal stringer resting upon said frame members, and rigid means xedly secured to a plurality of frame members, each means including a pair of rectilinear angle iron braces, each brace having a portion extending above the frame member to which it is secured in a vertical direction when the hull is on even keel, the vertical faces of said braces engaging opposite sides of said stringer and being bolted thereto for maintaining the depth dimension of said stringer vertical throughout.

4. In a boat hull having a plurality of longitudinally spaced transverse frame members extending from adjacent the bow to adjacent .the stern and varying in angularity with respect to the keel to which they are attached, a plurality of transversely spaced longitudinally extending stringers, eachbowed both vertically and transversely and each resting with a narrow edge engaging the top edges of said frame members, and means for rigidly securing said stringers to said frame members with their Side faces vertical srhroughout their length when the hull is on even eel.

5. In a boat hull having a plurality of longitudinally spaced transverse frame members arranged in pairs of varying angularity, said frame members formed with spaced horizontal notches, a plurality oi transversely spaced longitudinally extending strngers of greater width than thickness arranged with their bottom narrow edges engaging aligned horizontal notches in said frame members, said stringere bowed both transversely and vertically, with means lfor rigidly securing said stringers to the frames with their sides vertical throughout, said stringers extending substantially from bow to stern of the hull.

ANDREW J. HIGGINS. 

